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Viral vector-based reversible neuronal inactivation and behavioral manipulation in the macaque monkey.

Nielsen KJ, Callaway EM, Krauzlis RJ - Front Syst Neurosci (2012)

Bottom Line: In principle, they can manipulate neurons at a level of specificity not otherwise achievable.While many studies have used viral vector-based approaches in the rodent brain, only a few have employed this technique in the non-human primate, despite the importance of this animal model for neuroscience research.We confirmed that these deficits indeed were due to the interaction of AlstR and AL by injecting saline, or AL at a V1 location without AlstR expression.

View Article: PubMed Central - PubMed

Affiliation: Systems Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla CA, USA.

ABSTRACT
Viral vectors are promising tools for the dissection of neural circuits. In principle, they can manipulate neurons at a level of specificity not otherwise achievable. While many studies have used viral vector-based approaches in the rodent brain, only a few have employed this technique in the non-human primate, despite the importance of this animal model for neuroscience research. Here, we report evidence that a viral vector-based approach can be used to manipulate a monkey's behavior in a task. For this purpose, we used the allatostatin receptor/allatostatin (AlstR/AL) system, which has previously been shown to allow inactivation of neurons in vivo. The AlstR was expressed in neurons in monkey V1 by injection of an adeno-associated virus 1 (AAV1) vector. Two monkeys were trained in a detection task, in which they had to make a saccade to a faint peripheral target. Injection of AL caused a retinotopic deficit in the detection task in one monkey. Specifically, the monkey showed marked impairment for detection targets placed at the visual field location represented at the virus injection site, but not for targets shown elsewhere. We confirmed that these deficits indeed were due to the interaction of AlstR and AL by injecting saline, or AL at a V1 location without AlstR expression. Post-mortem histology confirmed AlstR expression in this monkey. We failed to replicate the behavioral results in a second monkey, as AL injection did not impair the second monkey's performance in the detection task. However, post-mortem histology revealed a very low level of AlstR expression in this monkey. Our results demonstrate that viral vector-based approaches can produce effects strong enough to influence a monkey's performance in a behavioral task, supporting the further development of this approach for studying how neuronal circuits control complex behaviors in non-human primates.

No MeSH data available.


Related in: MedlinePlus

Results of the post-mortem histology. (A–C) V1 sections stained for GFP. Cells stained black are GFP-positive, which is co-localized with AlstR expression. Scale bar: 100 μm. (A) Tissue from monkey W. (B) Section of V1 at the first virus injection site in monkey V. (C) V1 section at the second injection site in monkey V. (D–F) Spatial profile of labeling density for an example section for each injection site. The gray scale level in this figure indicates the density of neurons computed within windows of 100 μm radius (see Materials and Methods). The white line markes the boundary of the area in each section that contained labeled cells. Yellow lines indicate the transition from gray matter to white matter (marked “WM”), and from brain to pia (marked “P”). Scale bar: 100 μm. (D) Monkey W. (E) First injection site in monkey V. (F) Second injection site in monkey V.
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Figure 3: Results of the post-mortem histology. (A–C) V1 sections stained for GFP. Cells stained black are GFP-positive, which is co-localized with AlstR expression. Scale bar: 100 μm. (A) Tissue from monkey W. (B) Section of V1 at the first virus injection site in monkey V. (C) V1 section at the second injection site in monkey V. (D–F) Spatial profile of labeling density for an example section for each injection site. The gray scale level in this figure indicates the density of neurons computed within windows of 100 μm radius (see Materials and Methods). The white line markes the boundary of the area in each section that contained labeled cells. Yellow lines indicate the transition from gray matter to white matter (marked “WM”), and from brain to pia (marked “P”). Scale bar: 100 μm. (D) Monkey W. (E) First injection site in monkey V. (F) Second injection site in monkey V.

Mentions: At the end of the experiment, we confirmed AlstR expression by post-mortem histology. AlstR-expressing neurons were identified by staining for GFP. The virus injection site was clearly visible as a region containing dense label (see Figure 3A for an example). We quantified the efficiency of virus injection by computing the density of infected neurons at the injection site. For this purpose, we counted the number of neurons labeled with GFP in consecutive sections spaced 400 μm apart. Cell counts were Abercrombie corrected to account for the distortion of cell counts in sectioned tissue (Guillery, 2002). Glial cells could be distinguished from neurons based on their different morphology and were excluded from the cell count. For each section, we also determined the volume of the tissue containing labeled neurons (see Materials and Methods), to compute the density of GFP labeled neurons for each section. The results of this analysis are listed in Table 1. We also computed a rough estimate of the fraction of neurons infected in each section, by comparing the density of labeled neurons per section to the density of neurons in macaque cortex as determined by Beaulieu et al. (Beaulieu et al., 1992). Differences between layers were not taken into account in this analysis. It should be noted that counting cells expressing GFP will result in an underestimate of AlstR-expressing neurons for the following reason: AlstR expression and GFP expression were coupled using an IRES2 element. As a consequence, while all GFP-positive neurons will also express the AlstR, there will be cells expressing the AlstR that are not GFP-positive (Mizuguchi et al., 2000). The density of infected cells reported here is, therefore, only a lower bound on the true infection efficiency.


Viral vector-based reversible neuronal inactivation and behavioral manipulation in the macaque monkey.

Nielsen KJ, Callaway EM, Krauzlis RJ - Front Syst Neurosci (2012)

Results of the post-mortem histology. (A–C) V1 sections stained for GFP. Cells stained black are GFP-positive, which is co-localized with AlstR expression. Scale bar: 100 μm. (A) Tissue from monkey W. (B) Section of V1 at the first virus injection site in monkey V. (C) V1 section at the second injection site in monkey V. (D–F) Spatial profile of labeling density for an example section for each injection site. The gray scale level in this figure indicates the density of neurons computed within windows of 100 μm radius (see Materials and Methods). The white line markes the boundary of the area in each section that contained labeled cells. Yellow lines indicate the transition from gray matter to white matter (marked “WM”), and from brain to pia (marked “P”). Scale bar: 100 μm. (D) Monkey W. (E) First injection site in monkey V. (F) Second injection site in monkey V.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3378014&req=5

Figure 3: Results of the post-mortem histology. (A–C) V1 sections stained for GFP. Cells stained black are GFP-positive, which is co-localized with AlstR expression. Scale bar: 100 μm. (A) Tissue from monkey W. (B) Section of V1 at the first virus injection site in monkey V. (C) V1 section at the second injection site in monkey V. (D–F) Spatial profile of labeling density for an example section for each injection site. The gray scale level in this figure indicates the density of neurons computed within windows of 100 μm radius (see Materials and Methods). The white line markes the boundary of the area in each section that contained labeled cells. Yellow lines indicate the transition from gray matter to white matter (marked “WM”), and from brain to pia (marked “P”). Scale bar: 100 μm. (D) Monkey W. (E) First injection site in monkey V. (F) Second injection site in monkey V.
Mentions: At the end of the experiment, we confirmed AlstR expression by post-mortem histology. AlstR-expressing neurons were identified by staining for GFP. The virus injection site was clearly visible as a region containing dense label (see Figure 3A for an example). We quantified the efficiency of virus injection by computing the density of infected neurons at the injection site. For this purpose, we counted the number of neurons labeled with GFP in consecutive sections spaced 400 μm apart. Cell counts were Abercrombie corrected to account for the distortion of cell counts in sectioned tissue (Guillery, 2002). Glial cells could be distinguished from neurons based on their different morphology and were excluded from the cell count. For each section, we also determined the volume of the tissue containing labeled neurons (see Materials and Methods), to compute the density of GFP labeled neurons for each section. The results of this analysis are listed in Table 1. We also computed a rough estimate of the fraction of neurons infected in each section, by comparing the density of labeled neurons per section to the density of neurons in macaque cortex as determined by Beaulieu et al. (Beaulieu et al., 1992). Differences between layers were not taken into account in this analysis. It should be noted that counting cells expressing GFP will result in an underestimate of AlstR-expressing neurons for the following reason: AlstR expression and GFP expression were coupled using an IRES2 element. As a consequence, while all GFP-positive neurons will also express the AlstR, there will be cells expressing the AlstR that are not GFP-positive (Mizuguchi et al., 2000). The density of infected cells reported here is, therefore, only a lower bound on the true infection efficiency.

Bottom Line: In principle, they can manipulate neurons at a level of specificity not otherwise achievable.While many studies have used viral vector-based approaches in the rodent brain, only a few have employed this technique in the non-human primate, despite the importance of this animal model for neuroscience research.We confirmed that these deficits indeed were due to the interaction of AlstR and AL by injecting saline, or AL at a V1 location without AlstR expression.

View Article: PubMed Central - PubMed

Affiliation: Systems Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla CA, USA.

ABSTRACT
Viral vectors are promising tools for the dissection of neural circuits. In principle, they can manipulate neurons at a level of specificity not otherwise achievable. While many studies have used viral vector-based approaches in the rodent brain, only a few have employed this technique in the non-human primate, despite the importance of this animal model for neuroscience research. Here, we report evidence that a viral vector-based approach can be used to manipulate a monkey's behavior in a task. For this purpose, we used the allatostatin receptor/allatostatin (AlstR/AL) system, which has previously been shown to allow inactivation of neurons in vivo. The AlstR was expressed in neurons in monkey V1 by injection of an adeno-associated virus 1 (AAV1) vector. Two monkeys were trained in a detection task, in which they had to make a saccade to a faint peripheral target. Injection of AL caused a retinotopic deficit in the detection task in one monkey. Specifically, the monkey showed marked impairment for detection targets placed at the visual field location represented at the virus injection site, but not for targets shown elsewhere. We confirmed that these deficits indeed were due to the interaction of AlstR and AL by injecting saline, or AL at a V1 location without AlstR expression. Post-mortem histology confirmed AlstR expression in this monkey. We failed to replicate the behavioral results in a second monkey, as AL injection did not impair the second monkey's performance in the detection task. However, post-mortem histology revealed a very low level of AlstR expression in this monkey. Our results demonstrate that viral vector-based approaches can produce effects strong enough to influence a monkey's performance in a behavioral task, supporting the further development of this approach for studying how neuronal circuits control complex behaviors in non-human primates.

No MeSH data available.


Related in: MedlinePlus